1. Technical Field
The present disclosure generally relates to automatic control technology, and particularly to a control method and a device utilizing a PID controller, and a robot applying the device.
2. Description of the Related Art
A proportional-integral-derivation controller (PID controller) is a generic control loop feedback device widely used in industrial control systems, such as robot manipulator controlling systems. The popularity of PID controllers can be attributed partly to their robust performance in a wide range of operating conditions and partly to their functional simplicity, which allows engineers to operate them in a simple, straightforward manner.
A PID controller attempts to correct an error between a measured process variable and a desired setpoint by calculating and then outputting a corrective action that can adjust the process accordingly and rapidly, to keep the error minimal. The PID controller calculation (algorithm) involves three basic coefficients: the proportional (Kp), the integral (Ki) and derivative (Kd). The proportional value determines the reaction to the current error, the integral value determines the reaction based on the sum of recent errors, and the derivative value determines the reaction based on the rate at which the error has been changing. The weighted sum of these three actions is used to adjust the process via a control element such as the position of a control valve or the power supply of a driving element. By tuning the three coefficients in the PID controller algorithm, the controller can provide control actions designed for specific process requirements.
A commonly used method for adjusting the three coefficients of a PID controller is manual tuning. For example, when adjusting the PID controller applied by a robot manipulator, Kp is increased to shorten response time and minimize oscillation. However, too much Kp will cause instability, and the manipulator will vibrate intensely. Therefore Kp is adjusted to an optimize PID controller performance while manually controlling the vibration. After repeated manual tunings, an optimum Kp is obtained. However, this adjustment of the Kp wastes time and is dependent upon tester intuition and experience. Additionally, in the case of the same system, the reference variables and the reference values applied to a specific operation state are not applied optimally to another state of the same system.
Therefore, there is room for improvement within the art.